Transparent is not the same as white
A white background is still painted white. It will show up as a white box when you put the image on a dark or colored page. A transparent background has no paint there. Design tools, store builders, and slides can show whatever is behind the subject.
If your file is a product or logo sitting on white, read how to remove a white background before you assume the white is already transparent.
How to read the checkerboard
The gray checkerboard in the preview is a stand-in so you can see empty pixels. It is not printed into the PNG. If you open the download on a white page, the empty area looks white. Open it on a colored page, or in a tool that shows transparency, to confirm the background is gone.
Use the PNG after you download it
- Place it on a new color in a design or slide tool.
- Upload it to a shop that accepts transparent PNG product images.
- Keep the original photo if you still need the version with the background.
The longer explanation of alpha and how to verify a file is in how to make an image background transparent.